1. Field of the Invention
This invention relates to improvements in scanning a two-dimensional images from multiple sheets of paper. More particularly, this invention uses a two-dimensional image sensor array to scan a single sheet of paper, and move the next sheet into position to be scanned.
2. Description of the Related Art
Electronic document technology requires a method of electronically inputting pages of text into some memory device. The conventional method is to use a linear scanner and mechanically move the documents across the scanner, or the scanner across the document. These devices have an input paper tray, an output paper tray and a distinct scanner module. The scanner module usually includes the illumination source and an optical focusing device, which is either a SELFOC lens or more conventional optics. These devices tend to be bulky because of the size of the optical focusing device and the illumination source must be bright.
The movement of the documents must be precise because the scanners usually only scan a single line or a few lines at a time. There is often a registration problem associated with uncontrolled paper motion which results in distortion of the image. Sometimes the scanner must make three passes across each line for color images. Therefore, these devices tend to be slow and scanning a single page document could take longer than a minute.
Addressable two-dimensional image sensor arrays made from amorphous silicon were conceived by M. Matsumura et al (IEEE Electron Device Letters, vol. EDL-1, page 182, 1980) and were demonstrated by Street et al (Material Research Society Symposium Proceedings, vol. 192, page 441, 1990). The use of these arrays for contact imaging was reported by Powell et al (Material Research Society Symposium Proceedings, vol. 258, page 1127, 1992).
Document handlers are widely used in copiers and printers. The techniques of transferring paper between input and output trays and of inverting sheets of paper are well known. However, such document handlers have not been applied to a device in which a scanner is incorporated in either the input or output tray.